Anyone familiar with seeder implements knows seeder row units do not have enough weight to consistently penetrate the soil to the intended planting depth. Down force actuators, such as mechanical springs, air bags or hydraulic cylinders overcome this limitation by transferring weight from the frame of the implement to the row unit.
Original actuators could not be controlled on-the-go. Now on-the-go down force actuator control systems are commonplace. Some embodiments are disclosed in EP 0372901 and U.S. Pat. No. 6,701,857. A sensor is used to measure how hard the row unit is pushing against the soil. If the row unit is not pushing against the soil, meaning planting is too shallow, the control system commands the down force actuator to apply more down force to the row unit. If the row unit is pushing against the soil too hard, the control system commands the down force actuator to remove down force.
On-the-go down force control systems usually have two or more rows instrumented with down force sensors per channel or section of control. Multiple sensors per section work well with prior art down force controllers as long as all sensed rows are in a part of the field that requires planting. In practice, sections of down force control occasionally span across areas of “no plant zones” and “plant zones.” Common examples are wide seeders in odd shaped fields or fields with grassed waterways.
What is needed is a control system that applies the correct down force on rows in a control section(s) spanning across no plant and plant zones. The problem is that existing down force control systems treat down force sensors in no plant and plant zones the same. The wrong down force gets applied to rows over the plant zone when the no plant zone soil is drastically different than the plant zone soil. For example, the system will apply too much down force on rows over a plant zone soft soil when one or more of the down force sensors is in a no plant zone, like a waterway, are over hard soil. The control system will apply more down force to all rows in that section to compensate for the one row that is sensing hard soil in the no plant zone. One example of such a system is disclosed in U.S. patent application 2010/0198529.
What is needed is a down force control system with improved control functions.